Detailed studies of protein synthesis during oogenesis, preimplantation development and early postimplantation development will be undertaken using one and two-dimensional polyacrylamide gel electrophoretic systems. The effects of actinomycin D on the synthesis of specific proteins will be examined, and comparisons will be carried out between protein synthesis in early embryos and in cultured teratocarcinoma cells. BIBLIOGRAPHIC REFERENCES: Epstein, C. J.: Gene expression and macromolecular synthesis during preimplantation embryonic development. Biol. Reprod. 12: 81, 1975. Erickson, R. P., Hoppe, P. C., Tennebaum, D., Spielmann, H., Epstein, C. J.: Lactate Dehydrogenase X: effects of antibody on mouse gametes but not on early development. Science 188: 261, 1975.